Distribution Characteristics and Main Influencing Factors of Organic Carbon in Sediments of Spartina Alterniflora Wetlands along the Northern Jiangsu Coast, China

In this study, columnar sediment samples were collected from north to south along the northern Jiangsu coast, China, under Spartina alterniflora vegetation in four sample areas: Chuandong Port (Area-1), Tiaozini Scenic Area (Area-2), Yangkou Town (Area-3), and Meiledi Marine Park (Area-4). Organic carbon (OC), nutrient elements including total nitrogen (TN), total phosphorus (TP), and total sulfur (TS), and physicochemical properties including pH, salinity (Sal), moisture content (MC), and bulk density (BD) were measured. Pearson’s correlation analysis was performed to explore the correlation between OC content and sedimentary physicochemical indexes, and the partial least squares regression (PLSR) model was used to analyze the factors affecting changes in OC content. The results found that the OC content of columnar sediments of S. alterniflora decreased with increasing depth in all four areas. The OC content in the four sample areas was mainly affected by the TN, pH, MC, TP, and burial depth. In particular, TN, MC, TP, TS, and clay content positively affected OC, whereas burial depth, pH, silt content, BD, sand content, and Sal negatively affected OC. The results of this study provide a valuable reference for evaluating the role of coastal wetlands in the global carbon cycle.